The present invention relates generally to the art of tapping conduits and, more particularly, to the art of tapping mains and service lines for purposes of replacing same without interrupting service. The invention will be described in connection with gas mains and service lines, but those of ordinary skill in the art will quickly recognize that the invention has broader application to other mains and service lines, especially those designed to supply a fluid to a recipient in a non-interruptible fashion.
In the installation of new natural gas mains, it is typical to bury the new main in the desired location (usually in parallel with an existing main) and thereafter connect the existing or new service lines thereto for purposes of supplying gas to recipients by way of respective service lines. FIG. 1 illustrates a prior installation for the transmission of natural gas from a buried main conduit 10 to a home, business or other recipient 15. Gas is withdrawn from the main 10 through a main tee 12, and a gas service line 14 fluidically connects the branch passage of the main tee 12 to the recipient 15, typically by way of a meter (not shown). Because older gas mains and older service lines were typically fabricated from iron, these elements corrode and must be replaced. In each case, plastic conduit is a preferred replacement.
Often, the gas service line 14 is a plastic conduit that has been inserted into a preexisting iron or other metallic service line conduit 13 for the purpose of “insert-renewing” the gas service to the recipient 15. In such an operation, the plastic conduit 14 is slidably inserted into the existing conduit 13 from the recipient end and the distal end of the plastic conduit is sealingly engaged with the existing metallic conduit adjacent the main 10 to prevent gas flow between the existing and new service line conduits. This insert-renewing operation has been found to be a highly effective and convenient means for replacing an obsolete service line conduit 13.
Heretofore, installation of a new main has involved simply cutting or blocking the relevant conduits and inserting the new conduits into the gas-flow circuit via tapping tees. For example, with continuing reference to FIG. 1, the service line 14 could be severed at the point 18 and thereafter connected to a new main. This, of course, interrupts service to recipients downstream relative to the cut 18. With gas transmission systems, interruption of service results in the extinguishment of pilot lights, and these must be re-lit by service personnel when gas service is restored. Furthermore, a significant amount of air often enters the gas transmission circuit and must be bled before the pilot lights will remain lit. The interruption of gas service during the main and/or service line replacement operation is highly undesirable and adds expense and inconvenience to the operation while lengthening the time recipients are without service.
Another deficiency associated with respect to prior main and/or service line replacement is that prior tapping tees are not well-suited for use on small-diameter plastic conduit, e.g., conduit with less than a two inch outer diameter. With conventional tapping tees, such conduit sometimes partially collapses during the tapping operation, and this prevents the formation of a good seal between the body of the tapping tee and the outer surface of the conduit.
In light of the foregoing specifically noted deficiencies and others associated with convention tapping tees and methods, it has been deemed desirable to provide a new and improved tapping tee and method that overcome these deficiencies and that provide better overall results.